Kennedy's Crash Highlights Dangers of Ambien

After he smashed his Ford Mustang into a barrier near Capitol Hill early Thursday morning, Rhode Island Rep. Patrick Kennedy released a statement, saying that he had been disoriented by two prescription medications he had taken.

One of which was Ambien, a prescription sleep aid.

While Kennedy said he was "disoriented" in his statement, police officers described him as "intoxicated."

How could using Ambien, the nation's most widely used sleep aid, explain his behavior?

Kennedy's situation echoes a growing trend, police and toxicologists say. In some states, Ambien has made it onto the lists of the Top 10 drugs found in impaired motorists.

One doctor questioned Kennedy's decision to get behind the wheel with two prescription drugs in his system.

"To get in a car in the first place was dangerous," said Domenic Sica, a professor of medicine and pharmacology
at Virginia Commonwealth University.

Kennedy was taking Phenergan, an anti-nausea medication, along with Ambien. The anti-nausea medication could have had an "amplifier effect" when coupled with Ambien, Sica said.

The behavior it causes among motorists is startling: They smash into parked cars, drive the wrong way down busy highways, and weave in between lanes. Sometimes they don't have any recollection of getting behind the wheel when they are pulled over, according to various reports.

"It certainly seems to me that the warnings are not sufficiently clear to the general public," said Laura Liddicoat, a toxicologist at the Wisconsin State Laboratory of Hygiene who spoke to "Good Morning America" in March about the increasing problem of Ambien and drivers.

Liddicoat recently found that 187 drivers arrested in Wisconsin in the last five years had the prescription sleeping pill Ambien in their bloodstream.

"The driving was not just such that it was weaving within the lane," Liddicoat said. "It was driving on the entirely wrong side of the road and almost having head-on collisions."

In Washington, there were 78 impaired driving arrests involving Ambien last year, up from 56 the year before.

Washington State Patrol Sgt. Robert Sharpe pulled over one woman who had taken the prescribed dose of Ambien, but at the wrong time.

"They took the medication before they left work thinking it would kick in before they got home," Sharpe said. "Driving is a task that most people need to do every day, but they don't think about how maybe their medications are going to affect that."

He said that people who took Ambien should read all the information and warnings that come with the drug.

"Even though it's prescribed medication and it's been OK'd by their doctor to take, it's not actually good to take that medication and then get behind the wheel of a car," he said. "Ambien is categorized in our program as a central nervous system depressant and just the same types of effects that are encountered with alcohol."

Doctors also have reported a few instances of "sleepdriving," when Ambien users got out of their bed, into their car, and drove, but were asleep the entire time.

Experts say certain groups are more at risk of dangerous drowsiness -- women, people taking high doses of Ambien, and those who combine Ambien with other medications for anxiety, depression or other disorders.

Ambien's makers told "Good Morning America": "We are aware of reports of people driving while sleepwalking and those reports have been provided to the FDA as part of our ongoing post-marketing evaluation about the safety of our products."

There have been almost 27 million prescriptions of Ambien sold in the United States.